Verify layer tarstream

This adds verification for getting layer data out
of layerstore. These failures should only be possible
if layer metadata files have been manually changed
of if something is wrong with tar-split algorithm.

Failing early makes sure we don’t upload invalid data
to the registries where it would fail after someone
tries to pull it.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
(cherry picked from commit e29e580f7f)

layer/layer_test.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/docker/distribution/digest"
@@ -56,7 +57,7 @@ func newTestGraphDriver(t *testing.T) (graphdriver.Driver, func()) {
 	}
 }
 
-func newTestStore(t *testing.T) (Store, func()) {
+func newTestStore(t *testing.T) (Store, string, func()) {
 	td, err := ioutil.TempDir("", "layerstore-")
 	if err != nil {
 		t.Fatal(err)
@@ -72,7 +73,7 @@ func newTestStore(t *testing.T) (Store, func()) {
 		t.Fatal(err)
 	}
 
-	return ls, func() {
+	return ls, td, func() {
 		graphcleanup()
 		os.RemoveAll(td)
 	}
@@ -265,7 +266,7 @@ func assertLayerEqual(t *testing.T, l1, l2 Layer) {
 }
 
 func TestMountAndRegister(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	li := initWithFiles(newTestFile("testfile.txt", []byte("some test data"), 0644))
@@ -306,7 +307,7 @@ func TestMountAndRegister(t *testing.T) {
 }
 
 func TestLayerRelease(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	layer1, err := createLayer(ls, "", initWithFiles(newTestFile("layer1.txt", []byte("layer 1 file"), 0644)))
@@ -351,7 +352,7 @@ func TestLayerRelease(t *testing.T) {
 }
 
 func TestStoreRestore(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	layer1, err := createLayer(ls, "", initWithFiles(newTestFile("layer1.txt", []byte("layer 1 file"), 0644)))
@@ -472,7 +473,7 @@ func TestStoreRestore(t *testing.T) {
 }
 
 func TestTarStreamStability(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	files1 := []FileApplier{
@@ -668,7 +669,7 @@ func assertActivityCount(t *testing.T, l RWLayer, expected int) {
 }
 
 func TestRegisterExistingLayer(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	baseFiles := []FileApplier{
@@ -702,3 +703,69 @@ func TestRegisterExistingLayer(t *testing.T) {
 
 	assertReferences(t, layer2a, layer2b)
 }
+
+func TestTarStreamVerification(t *testing.T) {
+	ls, tmpdir, cleanup := newTestStore(t)
+	defer cleanup()
+
+	files1 := []FileApplier{
+		newTestFile("/foo", []byte("abc"), 0644),
+		newTestFile("/bar", []byte("def"), 0644),
+	}
+	files2 := []FileApplier{
+		newTestFile("/foo", []byte("abc"), 0644),
+		newTestFile("/bar", []byte("def"), 0600), // different perm
+	}
+
+	tar1, err := tarFromFiles(files1...)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tar2, err := tarFromFiles(files2...)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	layer1, err := ls.Register(bytes.NewReader(tar1), "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	layer2, err := ls.Register(bytes.NewReader(tar2), "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	id1 := digest.Digest(layer1.ChainID())
+	id2 := digest.Digest(layer2.ChainID())
+
+	// Replace tar data files
+	src, err := os.Open(filepath.Join(tmpdir, id1.Algorithm().String(), id1.Hex(), "tar-split.json.gz"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dst, err := os.Create(filepath.Join(tmpdir, id2.Algorithm().String(), id2.Hex(), "tar-split.json.gz"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := io.Copy(dst, src); err != nil {
+		t.Fatal(err)
+	}
+
+	src.Close()
+	dst.Close()
+
+	ts, err := layer2.TarStream()
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = io.Copy(ioutil.Discard, ts)
+	if err == nil {
+		t.Fatal("expected data verification to fail")
+	}
+	if !strings.Contains(err.Error(), "could not verify layer data") {
+		t.Fatalf("wrong error returned from tarstream: %q", err)
+	}
+}

layer/layer_unix_test.go

@@ -16,7 +16,7 @@ func graphDiffSize(ls Store, l Layer) (int64, error) {
 // Unix as Windows graph driver does not support Changes which is indirectly
 // invoked by calling DiffSize on the driver
 func TestLayerSize(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	content1 := []byte("Base contents")

layer/migration_test.go

@@ -268,7 +268,7 @@ func TestLayerMigrationNoTarsplit(t *testing.T) {
 }
 
 func TestMountMigration(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	baseFiles := []FileApplier{

layer/mount_test.go

@@ -11,7 +11,7 @@ import (
 )
 
 func TestMountInit(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	basefile := newTestFile("testfile.txt", []byte("base data!"), 0644)
@@ -63,7 +63,7 @@ func TestMountInit(t *testing.T) {
 }
 
 func TestMountSize(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	content1 := []byte("Base contents")
@@ -105,7 +105,7 @@ func TestMountSize(t *testing.T) {
 }
 
 func TestMountChanges(t *testing.T) {
-	ls, cleanup := newTestStore(t)
+	ls, _, cleanup := newTestStore(t)
 	defer cleanup()
 
 	basefiles := []FileApplier{

layer/ro_layer.go

@@ -1,6 +1,11 @@
 package layer
 
-import "io"
+import (
+	"fmt"
+	"io"
+
+	"github.com/docker/distribution/digest"
+)
 
 type roLayer struct {
 	chainID    ChainID
@@ -29,7 +34,11 @@ func (rl *roLayer) TarStream() (io.ReadCloser, error) {
 			pw.Close()
 		}
 	}()
-	return pr, nil
+	rc, err := newVerifiedReadCloser(pr, digest.Digest(rl.diffID))
+	if err != nil {
+		return nil, err
+	}
+	return rc, nil
 }
 
 func (rl *roLayer) ChainID() ChainID {
@@ -117,3 +126,39 @@ func storeLayer(tx MetadataTransaction, layer *roLayer) error {
 
 	return nil
 }
+
+func newVerifiedReadCloser(rc io.ReadCloser, dgst digest.Digest) (io.ReadCloser, error) {
+	verifier, err := digest.NewDigestVerifier(dgst)
+	if err != nil {
+		return nil, err
+	}
+	return &verifiedReadCloser{
+		rc:       rc,
+		dgst:     dgst,
+		verifier: verifier,
+	}, nil
+}
+
+type verifiedReadCloser struct {
+	rc       io.ReadCloser
+	dgst     digest.Digest
+	verifier digest.Verifier
+}
+
+func (vrc *verifiedReadCloser) Read(p []byte) (n int, err error) {
+	n, err = vrc.rc.Read(p)
+	if n > 0 {
+		if n, err := vrc.verifier.Write(p[:n]); err != nil {
+			return n, err
+		}
+	}
+	if err == io.EOF {
+		if !vrc.verifier.Verified() {
+			err = fmt.Errorf("could not verify layer data for: %s. This may be because internal files in the layer store were modified. Re-pulling or rebuilding this image may resolve the issue", vrc.dgst)
+		}
+	}
+	return
+}
+func (vrc *verifiedReadCloser) Close() error {
+	return vrc.rc.Close()
+}